How to setup rules around SSL VPN for Mac and Windows

Hi,

I have setup a SSL VPN correctly and it's working.

But I need to setup some rules for the laptop on our office.

I want to people can't have access to internet (except things needed to connect to the vpn using FortiClient) when they use a non-office network before they connect to the VPN.

And I need to do that for Windows and Mac laptops.

If someone have any idea how to achieve that it will be very helpful.

Many thanks,

Ben